Here we develop a monthly gridded dataset of northern (> 45 N) wetland methane (CH4) emissions. The data product is derived using random forest machine learning technique and eddy covariance CH4 fluxes from 25 wetland sites. Annual CH4 emissions from these wetlands calculated from the derived data product are comparable to prior studies focusing on these areas. This product is an independent estimate of northern wetland CH4 emissions and hence could be used e.g. for process model evaluation.

Ground thermal and moisture data are important indicators of the rapid permafrost changes in the Arctic. To better understand the changes, we need a comprehensive dataset across various sites. We synthesize permafrost-related data in the state of Alaska. It should be a valuable permafrost dataset that is worth maintaining in the future. On a wider level, it also provides a prototype of basic data collection and management for permafrost regions in general.

Using drones, satellite images and historic photos we surveyed a permafrost coastline on Qikiqtaruk–Herschel Island. We aimed to assess coastal change over small timesteps, relate short-term changes to longer-term changes, and assess drones as tools for surveying Arctic coastlines. In 2017, we observed coastal retreat of 14.5 m per year, more than six times faster than the long-term average rate of 2.2 m per year (1952–2017). Episodic changes are poorly understood in permafrost coastlines.

Peat constitutes a long-term archive for climate reconstruction by using the isotopic composition of carbon and oxygen. We analysed isotopes in two peat moss species across North America and Eurasia. Peat (moss tissue) isotope composition was predicted by soil moisture and isotopic composition of the rainwater but differed between species. Our results suggest that isotope composition can be used on a large scale for climatic reconstructions but that such models should be species-specific.

To improve microwave satellite and airborne observation products in forest environments, a precise and reliable estimation of the permittivity of trees is required. We developed a probe suitable to measure the permittivity of tree trunks at L band in the field. The system is easily transportable in the field, low energy consuming, operational at low temperatures and weatherproof. The permittivity of seven tree species in both frozen and thawed states was measured, showing important contrast.

Our work evaluated the appropriateness of the common steady-state (SS) assumption, for example when partitioning soil respiration of CO2 into recently photosynthesized carbon (C) and older C. Using a new model of soil CO2 production and transport we found that the SS assumption is valid most of the time, especially in sand/silt soils. Non-SS conditions occurred mainly for the few days following large rain events in all soil types, but the non-SS period was prolonged and magnified in clay soils.

Waterbodies are abundant in Arctic permafrost lowlands. Most waterbodies are ponds with a surface area smaller than 100 x 100 m. The Permafrost Region Pond and Lake Database (PeRL) for the first time maps ponds as small as 10 x 10 m. PeRL maps can be used to document changes both by comparing them to historical and future imagery. The distribution of waterbodies in the Arctic is important to know in order to manage resources in the Arctic and to improve climate predictions in the Arctic.

This is an interesting piece of work and makes a nice contribution to the knowledge on how aboveground vegetation can control belowground soil properties through functional traits and functional diversity. Functional traits are the center of recent attempts to unify key ecological theories on species coexistence and assembly in communities. The results presented are valuable for understanding the relationship between species traits, functional diversity, and soil properties.

We combined field data collection with remote sensing data to document the presence and rapid degradation of permafrost in south-central Alaska during 1950–present. Ground temperature measurements confirmed permafrost presence in the region, but remotely sensed images showed that permafrost plateau extent decreased by 60 % since 1950. Better understanding these vulnerable permafrost deposits is important for predicting future permafrost extent across all permafrost regions that are warming.

This study produced a high-resolution dynamical downscaling data set for the Alaskan North Slope and surrounding areas. It helps to resolve the problem of the sparse observation over this region, where routinely and accurately measuring climatic variables is extremely difficult. This data set boosts up multiple research projects that explore the various climatic impacts over the Alaskan North Slope of the past and the future.

This paper introduces the development process of a data set that specifically made for climatic impacts research over the Alaskan North Slope. This data set can offset to some extent the sparseness of observation on spatial and temporal scales, retrieving high-resolution climatic backgrounds that enable various studies in the fields of climatology, hydrology, ecology, etc.

Direct human impact on a catchment (fertilizer input, soil disturbance, urbanization) is asymmetrically linked with inherent catchment properties (geology, soil, topography), which together determine catchment vulnerability to human activity. To quantify the influence of physical, hydrologic, and anthropogenic controls on surface water quality, we used a 5-year high-frequency water chemistry data set from three contrasting headwater catchments in western France.

We found that dissolved organic carbon (DOC) in arctic soils and aquatic systems is increasingly degradable with increasing permafrost extent. Also, DOC seems less degradable when moving down the fluvial network in continuous permafrost regions, i.e. from streams to large rivers, suggesting that highly bioavailable DOC is lost in headwater streams. We also recommend a standardized DOC incubation protocol to facilitate future comparison on processing and transport of DOC in a changing Arctic.

As high latitudes warm, carbon and nitrogen stored in permafrost soil will be vulnerable to erosion and transport to Arctic streams and rivers. We sampled outflow from 83 permafrost collapse features in Alaska. Permafrost collapse caused substantial increases in dissolved organic carbon and inorganic nitrogen but decreased methane concentration by 90%. Upland thermokarst may be a dominant linkage transferring carbon and nutrients from terrestrial to aquatic ecosystems as the Arctic warms.

Beaded streams have deep elliptical pools connected by narrow runs that we show are common landforms in the continuous permafrost zone. These fluvial systems often initiate from lakes and occur predictably in headwater portions of moderately sloping watersheds. Snow capture along stream courses reduces ice thickness allowing thawed sediment to persist under most pools. Interpool thermal variability and hydrologic regimes provide important aquatic habitat and connectivity in Arctic landscapes.

Global forest resources are accounted for to establish their potential to sink carbon in woody biomass. Climate prediction models realize the effects of future global forest utilization rates, defined by population demand and its evolution over time. However, forest management approaches consider the supply side to realize a sustainable forest carbon stock and adapt the harvest rates to novel climate conditions. This study simulates such an adaptive sustained
yield approach.

The surface albedo time series CLARA-A2 SAL was used to study trends in the timing of the melting season of snow and preceding albedo value in Finland during 1982–2016 to assess climate change. The results were in line with operational snow depth data, JSBACH land ecosystem model, SYKE fractional snow cover and greening-up data. In the north a clear trend to earlier snowmelt onset, increasing melting season length, and decrease in pre-melt albedo (related to increased stem volume) was observed.

The paper revealed a potential structural deterioration induced by ocean acidification on the shells of an ecologically and economically important oyster, which is critical to forecasting the survival and production of edible oysters in the future ocean. Importantly, this is a multidisciplinary collaboration including aquaculture, crystallography, medical and materials science, which could be applied to other biomineral systems to hierarchically analyse the impact of ocean acidification.

Over the past decades temperate forests were a carbon (C) sink to the atmosphere. Yet the drivers of C uptake and how these affect the future carbon cycle remain uncertain. Our simulation and study revealed that the future C sink of central European forest landscapes is strongly driven by historic land use, while climate change reduces forest C uptake. Compared to land-use change, past natural disturbances (wind and bark beetles) have only marginal effects on the future carbon cycle.

Invertebrate species of the Gullmar Fjord (Sweden) were exposed to four different treatments (high/low oxygen and low/high CO2) and respiration measured. Respiration responses of species of contrasting habitats and life-history strategies to single and multiple stressors was evaluated. Results show that the responses of the respiration were highly species specific as we observed both synergetic as well as antagonistic responses, and neither phylum nor habitat explained trends in respiration.

How fast might the arctic treeline migrate northwards under current global warming in north-central Siberia? To answer this question, we parameterized our individual-based and spatially explicit model LAVESI-WIND based on a parentage analysis. Our simulation results show that migration of northernmost open forest stands into tundra seems to be unexpectedly slow. We conclude that the treeline currently lags behind the strong warming and will continue to lag in the near future.

To understand ecological impacts of CO2-induced ocean acidification and temperature rise, a key question is if organisms become more vulnerable under multiple stressors. Here we tested heart rate and gene expression levels of a limpet under varying pCO2 and temperature. Results showed that while many individuals are more vulnerable to heat stress under high CO2 and increased temperature, some animals have the ability to alter their physiology to help them survive under future conditions.

Compared to the respiration process, few studies have examined soil carbon leaching possibly enhanced by extreme precipitation events (EPEs). We show that soil carbon leaching was much higher than CO2 loss through respiration under EPEs in grassland soils through incubation experiments. The soil carbon leaching process should be incorporated into soil carbon models when estimating carbon balance in grassland ecosystems, especially considering the projected increase in EPEs with climate change.

We describe the evolution of thaw slumps between 1952 and 2011 along the Yukon Coast, Canada, and calculate the contribution of the slumps to the carbon budget in this area. The number of slumps has increased by 73 % over the period. These slumps displaced more than 16 billion m3 of material and mobilized 146 t of carbon. This represents 0.6 % of the annual carbon flux released from shoreline retreat, which shows that the contribution of slumps to the nearshore carbon budget is non-negligible.

A vegetation model was used to reconstruct fire activity from 1901 to 2012 in relation to changes in lightning ignition, climate, and vegetation in eastern Canada's boreal forest. The model correctly simulated the history of fire activity. The results showed that fire activity is ignition limited but is also greatly affected by both climate and vegetation. This research aims to develop a vegetation model that could be used to predict the future impacts of climate changes on fire activity.

We observed that N : P supply ratios had the strongest effect on C : N : P stoichiometry, while temperature and pCO2 played more influential roles on PIC : POC and polyunsaturated fatty acid proportions in Emiliania huxleyi. Synergistic interactions indicated the enhanced effect of warming under nutrient deficiency and high pCO2. Simultaneous changes of elements and fatty acids should be considered when predicting future roles of E. huxleyi in biogeochemical cycles and ecological functions.

The negative effects of elevated temperature (31 °C) on larval settlement of P. damicornis was greatly tempered by diurnal temperature fluctuations, whilst diel oscillations in temperature reduced the heat stress on photo-physiology of coral recruits. Although elevated temperature greatly stimulated the growth of recruits, the daytime encounters with the maximum temperature of 33 °C in the fluctuating treatment elicited a notable reduction in calcification.

Solar radiation management (SRM) is suggested as a method to offset global warming and to buy time to reduce emissions. Here we use an Earth system model to project the impact of SRM on future ocean biogeochemistry. This work underscores the complexity of climate impacts on ocean primary production and highlights the fact that changes are driven by an integrated effect of many environmental drivers, which all change in different ways.

This study is the first to examine how permafrost slumping affects dissolved organic carbon (DOC) mobilization in landscapes dominated by glacial tills. Unlike in previous studies, we find that slumping is associated with decreased DOC concentrations in downstream systems – an effect that appears to occur via adsorption to fine-grained sediments. This work adds significantly to our understanding of varying effects of permafrost thaw on organic carbon mobilization across diverse Arctic regions.

The effects of C turnover time on ecosystem C storage have not been well explored, so we quantified the spatial variation in ecosystem C storage over time from changes in C turnover time and/or NPP. Our results showed that the terrestrial C release caused by the decrease in MTT only accounted for about 13.5 % of that due to the change in NPP uptake. However, the larger uncertainties in the spatial variation of MTT than temporal changes would lead to a greater impact on ecosystem C storage.

El Niño–Southern Oscillation (ENSO) has been identified as one of the main drivers for the interannual variability in eastern African rainfall. But we know little about its direct impact on vegetation and how it might change in the future. In this study, we quantified this relationship and predict its future under certain climate change scenarios. Results suggest that we need to consider an increase in future ENSO intensity to cover the full range of potential changes in vegetation responses.

Experiments that manipulate the temperature of plants and ecosystems are used to improve understanding of how they will respond to climate change. In logistically challenging locations passive warming using solar energy is the the only viable option for warming experiments. Unfortunately current passive warming approaches can only raise air temperature by about 1.5 °C. We have developed a novel approach that doubles the warming possible using solar energy and requires no power.

We studied the effects of summer heatwaves and drought on photosynthesis and isoprene emissions in black locust trees. While photosynthesis decreased, isoprene emission increased sharply during the heatwaves. Comparing isoprene emissions of stressed and unstressed trees at the same temperature, however, demonstrated that stressed trees emitted less isoprene than expected. This reveals that in order to predict isoprene emissions during heat waves, model parameters need to be re-evaluated.

There are large reserves of carbon within the permafrost which might be released to the atmosphere under global warming. Our models suggest this release may cause an additional global temperature increase of 0.005 to 0.2°C by the year 2100 and 0.01 to 0.34°C by the year 2300. Under climate mitigation scenarios this is between 1.5 and 9 % (by 2100) and between 6 and 16 % (by 2300) of the global mean temperature change. There is a large uncertainty associated with these results.

We conducted a field manipulation experiment by redistributing 67 % of dry-season rainfall into the wet season while keeping the annual rainfall unchanged in a subtropical forest. Soil net nitrification and N mineralization rates were decreased by 13–20 % in the dry season and increased by 50 % with an accelerated NO3 leaching in the wet season. Functional microbial gene abundance and microbial biomass were the main factors affecting the N-process responses to the rainfall seasonality changes.

Single-celled living calcareous planktic foraminifera data across the Mediterranean Sea suggest that stratification of the surface water column, food availability, temperature, and seawater carbonate chemistry are the main factors controlling their distribution and mass. Increasing temperature, salinity, surface ocean stratification, and trophic conditions could be the causes of reduced abundance, diversity and species-specific changes in calcification in planktic foraminifera.

We report regional-scale erosion of coral reef ecosystems in the Atlantic, Caribbean, and Pacific oceans determined by measuring changes in seafloor elevation. The magnitude of seafloor elevation loss has increased local sea level rise, causing water depths not predicted until near 2100, placing coastal communities at elevated and accelerating risk from hazards such as waves, storms, and tsunamis. Our results have broad implications for coastal resource and safety management.

We analyzed the evolution of the atmospheric CO2 mean annual cycle simulated during 1950–2300 under three scenarios designed to separate the effects of climate change, CO2 fertilization, and land use change. CO2 fertilization in boreal and temperate ecosystems drove mean annual cycle amplification over the NH midlatitudes during 1950–2300. Boreal and Arctic climate change drove high-latitude amplification before 2200, after which CO2 fertilization contributed nearly equally to amplification.

The use of 15N natural abundance of soil ammonium and nitrate demonstrates a clear shifting contribution from abiotic to biotic controls on N cycling along a 3200 km dryland transect in northern China, with a threshold at mean annual precipitation of 100 mm. Abiotic factors were the main driver below threshold, shown by the accumulation of atmospheric N and NH3 losses. In the area above threshold, soil N cycling was controlled mainly by biological factors, e.g., plant uptake and denitrification.

Savannas are extensive yet sensitive to variability in precipitation. We examined the relationship between climate phenomena and historical rainfall variability across Australian savannas using 16 climate indicies. Seasonal variation was most correlated with the Australian Monsoon Index, whereas interannual variability was related to a greater number of phenomena. Rainfall variability and the underlying climate processes driving variability are important.

Ocean acidification (OA) in the near future is affecting several marine organisms negatively. To increase our understanding of the effects we studied embryos and larvae of the great scallop. They were exposed to an increasing level of OA, from natural seawater to levels expected in 50–100 years from now. Larvae were negatively affected already after 2 days, and fed larva seemed as sensitive as unfed larvae after 7 days.
Adaption and acclimatization may counteract future OA effects on scallops.

Marine biota drives a number of climate-relevant mechanisms, not all of which are included in current Earth system models (ESMs) used for climate projections. We identify three classes of mechanisms and argue that, to adequately resolve these mechanisms and to ensure links to and feedbacks with other Earth system components, ESMs need to account for five marine organism groups.

The use of ocean gliders, a class of underwater vehicles for observing the ocean to understand biogeochemical and physical processes, has been pioneered in the North Sea as part of the coastal observatory COSYNA. Since gliders go slow, strong tidal currents are problematic for their navigation. To predict (

Ongoing ocean acidification is being superimposed on the natural carbonate buffer system to influence the physiology of phytoplankton. Here, we show that coastal and oceanic diatoms respond differentially to diurnal fluctuating carbonate chemistry in current and ocean acidification scenarios. We propose that the ability to acclimate to dynamic carbonate chemistry may act as one determinant of the spatial distribution of diatom species.

We investigated forest albedo and FAPAR in Alaska and Finland in the boreal zone, using a radiative transfer model parameterized with forest inventory data. Albedo and canopy FAPAR were tightly connected in coniferous forests, indicating that managing forests to increase albedo may compromise productivity. Alaskan and Finnish forests differed in their albedo and FAPAR values, and solar elevation was an important factor controlling the relationships between forest structure, albedo, and FAPAR.

Our work provides a new coral proxy-based reconstruction of sea surface temperature (SST) from the coral reefs of Rodrigues Island, located in the poorly studied south-central Indian Ocean trade wind belt. This site is well located to study the SST history of the subtropical Indian Ocean and its teleconnections with the Pacific over long timescales. Our results provide insights into biases in coral Sr / Ca-based SST reconstructions and how to avoid them.

Considering air temperature as a direct predictor of heat stress is misleading as physiological consequences from heat depend on tissue temperatures. This study helps to clarify more fundamentally when and how heat waves may lead to plant stress by demonstrating how several environmental variables contribute to tissue temperatures. This renders it easier for ecologists and agronomists to predict when the dangers of heat stress occurring are highest.

In this study we systematically quantify simultaneities between meteorological extremes and the timing of flowering of four shrub species across Germany by using event coincidence analysis. Our study confirms previous findings of experimental studies, highlighting the impact of early spring temperatures on the flowering of the investigated plants. Additionally, the analysis reveals statistically significant indications of an influence of temperature extremes in the fall preceding the flowering.

We evaluated relations between sapwood carbohydrate content and wood formation in Quercus robur and the more drought-tolerant Q. pyrenaica along a water-availability gradient in the NW Iberian Peninsula. Winter carbohydrate levels and wood production decreased under more humid conditions for both species. Our results also suggest that sugar levels in sapwood modulate earlywood production in Q. pyrenaica, which showed a more conservative carbon use strategy than Q. robur.

Global NPP and EP are reduced considerably for RCP8.5. Negative response of NPP and EP to stratification increases reflects a bottom-up control. Models with dynamic phytoplankton community structure show larger declines in EP than in NPP driven by phytoplankton community composition shifts. Projections of the NPP response to climate change depend on the phytoplankton community structure, the efficiency of the biological pump and the levels of regenerated production.

Bacterial extracellular enzymes play a significant role in the degradation of organic matter in the open ocean. Using artificial fluorogenic substrates, this research highlights potential artefacts in the response of bacterial glucosidase and aminopeptidase to ocean acidification, and the effects of three different acidification techniques. We conclude that fluorogenic substrate degradation is affected by, or alters pH, and bubbling CO2 may lead to the overestimation of carbohydrate degradation.

We demonstrate the potential of spaceborne data for integrating forest height and density to assess forest structure for patches in the taiga–tundra ecotone. We map forest patches at sites in northern Siberia with spaceborne data and examine the uncertainty of forest patch height estimates across these ecotone sites. Results demonstrate the opportunities for improving patch-based spaceborne estimates of forest height and forest structure patterns in the circumpolar domain.

The improved LPJ model was used to investigate plant functional type (PFT) changes in 1957–2009 and their responses to changes in root zone soil temperature, soil moisture, air temperature, precipitation, and CO2 concentrations. The results show spatially heterogeneous changes in PFTs in the northern Tibetan Plateau in 1957–2009. Dominant driver for PFT change is precipitation. The implications of the study are on the regional fresh water resources, onset, and intensity of monsoon circulations.

We studied the responses of larvae of Macoma balthica to a range of future CO2 scenarios using large mesocosms encompassing the entire pelagic community. We focused on the growth and settlement process of M. balthica when exposed to future CO2 levels, and found the size and time to settlement to increase along the CO2 gradient, suggesting a developmental delay. The strong impact of increasing CO2 on early-stage bivalves is alarming as these stages are crucial for sustaining viable populations.

Bimodality is found in aboveground biomass and mean annual shortwave radiation in West Africa, which is a strong evidence of alternative stable states. The condition with low biomass and low radiation is demonstrated under which ecosystem state can shift between savanna and forest states. Moreover, climatic indicators have different prediction confidences to different land cover types. A new method is proposed to predict potential land cover change with a combination of climatic indicators.

This research reveals new insights into the weather drivers of land surface phenology (LSP) across the entire European forest, while at the same time it establishes a new conceptual framework for modelling LSP. Specifically, a sophisticated machine learning regression method (RF) was introduced for LSP modelling across very large areas and across multiple years simultaneously. The RF models explained 81 and 62 % of the variance in the spring and autumn LSP interannual variation.

Recent Southern Hemisphere (SH) atmospheric circulation, predominantly driven by stratospheric ozone depletion over Antarctica, has caused changes in climate across the extratropics. We present evidence that the Brazilian coast may have been impacted from both wind and sea surface temperature changes derived from this process. Skeleton analysis of massive coral species living in shallow waters off Brazil are very sensitive to air–sea interactions and seem to record this process.

We simulated both fire pulses and stable fire regimes and found the resulting climatic impacts to be irreconcilable with equivalent amounts of CO2 emissions produced by fossil fuel combustion. Consequently, side-by-side comparisons of fire and fossil fuel CO2 emissions—implicitly implying that they have similar effects—should be avoided. Our study calls for the explicit representation of fire in climate models in order to improve our understanding of its impacts in the Earth system.

The soils of the permafrost region are estimated to hold 1100 to 1500 billion tonnes of carbon. As climate change progresses much of this permafrost is expected to thaw and the carbon within it decay. Here we conduct numerical experiments with a climate model to estimate with formal uncertainty bounds the release of carbon from permafrost soils. Our simulations suggest that the permafrost carbon will make a significant but not cataclysmic contribution to climate change over the next centuries.

We investigate the properties of soils and sediments in a particular and ancient Siberian permafrost landscape. We critically examine statements from a recent study that specific permafrost landforms affected by thawed permafrost (alases) in this region contain very large quantities of peat that previous studies had failed to include because of data set biases. We conclude that there is no evidence to suggest biases in existing data sets or that alas deposits increase the northern peatland pool.

Lake Ohrid (Macedonia, Albania) is thought to be more than 1.2 million years old. To recover a long paleoclimate record for the Mediterranean region, a deep drilling was carried out in 2013 within the scope of the Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO) project. Here, we present lithological, sedimentological, and (bio-)geochemical data from the upper 247.8 m composite depth of the overall 569 m long DEEP site record.

Kasischke, E. and Turetsky, M.: Recent changes in the fire regime across the North American boreal region-spatial and temporal patterns of burning across Canada and Alaska, Geophys. Res. Lett., 33, L09703, https://doi.org/10.1029/2006GL025677, 2006.

Vegetation and soils strongly influence ground temperature in permafrost ecosystems across the Arctic and sub-Arctic. These effects will cause differences rates of permafrost thaw related to the distribution of tundra and boreal forests. As the distribution of forests and tundra change, the effects of climate change on permafrost will also change. We review the ecosystem processes that will influence permafrost thaw and outline how they will feed back to climate warming.